Method and apparatus for determining the dielectric constant of a low permittivity dielectric on a semiconductor wafer

ABSTRACT

In an apparatus and method for determining a permittivity of a dielectric layer on a semiconductor wafer, a thickness of the dielectric layer is determined and a topside of the wafer is moved into contact with a spherical portion of an at least partially spherical and electrically conductive surface. An electrical stimulus is applied between the electrically conductive surface and the semiconducting material. A capacitance of a capacitor comprised of the electrically conductive surface, the semiconductor material and the dielectric layer is determined from the applied stimulus. A permittivity of the dielectric layer is then determined as a function of the capacitance and the thickness of the dielectric layer.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to semiconductor wafer testing.

2. Description of Related Art

In multi-level metallizations in integrated circuits, an interlayerdielectric (ILD) electrically isolates adjacent metal layers. Thepermittivity (∈) or dielectric constant (k) of the ILD is, therefore, anincreasingly critical parameter as device dimensions shrink. By) way ofbackground, the permittivity (∈) of a material is equal to the productof the material's dielectric constant (k) times the permittivity (∈₀) offree space, i.e., ∈=(k) (∈₀).

Second generation low permittivity, or low-k, dielectric materials,synthesized by chemical vapor deposition or spin-casting techniques, arecurrently being developed. These low permittivity dielectrics includeboth inorganic (silicon-based) and organic (carbon-based) materials,often with controlled levels of porosity. The use of a dielectric layerhaving a lower permittivity than previous generations of semiconductordevices reduces RC time delays, prevents cross talk and reduces powerconsumption in devices by decreasing the parasitic capacitance of theILD layer.

Capacitance-voltage (CV) measurements on dielectric materials todetermine permittivity are often made with mercury probes. There areseveral disadvantages with utilizing mercury probes. First, a minimumthickness of dielectric material is required for measuring materialswith high permittivities. Second, new low permittivity materials(dielectric constants<3.9 (SiO₂)) are often porous, whereupon themercury contact area is affected. Third, new requirements forsemiconductor fabrication facilities increasingly ban the use ofmercury.

Similar to CV measurements, charge-voltage measurements on dielectricmaterials to determine the permittivity thereof have been recently madeutilizing corona-based methods. These methods are based on a depositionof charge onto the dielectric surface with a subsequent surface voltagemeasurement. Disadvantages of the corona-based method include the timeneeded to make each measurement, the large measurement spot size, andpoor likelihood that end users will allow for corona deposition ofproduct wafers.

CV measurements on dielectric materials utilizing conductive elasticprobes have been successful for measuring high permittivity, or high-k,materials down to a thickness of less than 1.0 nm. However, the currentdesign of these conductive elastic probes developed for highpermittivity materials cannot be used for measurement of lowpermittivity materials. This is due to the small contact diameter, e.g.,between 30 μm and 50 μm, of the conductive elastic probe in combinationwith a thicker, e.g., >200 μm thick, low permittivity film resulting ina weak electrical signal of only several pF. Moreover, according toHertzian calculations, the maximum pressure the prior art conductiveelastic probes can apply may cause yielding of many organic lowpermittivity films.

Therefore, what is needed is a method and apparatus for determining thepermittivity or dielectric constant, of the thicker, low permittivitydielectric layers on semiconductor wafers.

SUMMARY OF THE INVENTION

The invention is a method of determining a permittivity of a dielectriclayer of a semiconductor wafer. The method includes providing a meansfor contacting a topside of a semiconductor wafer. The contact meansincludes at least a partially spherical surface formed from a conductivematerial. A thickness of a dielectric layer on the semiconductor waferhaving semiconducting material underlying the dielectric layer isdetermined. The topside of the semiconductor wafer is caused to supportthe at least partially spherical surface of the contact means in spacedrelation to the semiconducting material thereby defining a capacitor. Anelectrical stimulus is applied to the contact means and thesemiconducting material when the capacitor is defined. A capacitance ofthe capacitor is determined from the response thereof to the appliedstimulus. The permittivity of the dielectric layer can then bedetermined as a function of the thus determined capacitance and thethickness of the dielectric layer determined above.

The topside of the semiconductor wafer includes at least one of (1) asurface of a dielectric layer opposite the semiconducting material or(2) a surface of organic(s) and/or water overlaying the surface of thedielectric layer opposite the semiconducting material.

The method can further include desorbing at least one of water andorganic(s) from the surface of the dielectric layer.

The at least partially spherical surface of the contact means can beformed from a material that either does not form an oxide layer or formsa conductive oxide. The contact means can be formed entirely from aconductive material or can be formed from a conductive or insulatingsubstrate having a conductive coating defining the at least partiallyspherical surface. One non-limiting example of a material from which thesubstrate can be formed includes glass.

The capacitance that is determined above includes the sum of (1) acapacitance where the topside of a semiconductor wafer supports thecontact means in spaced relation to the semiconducting material and (2)a capacitance of a gap between the contact means and the topside of thesemiconductor wafer adjacent where the topside of the semiconductorwafer supports the contact means in spaced relation to thesemiconducting material.

The permittivity of the dielectric layer (∈_(ox)) can be determinedutilizing the formula:

$\begin{matrix}{C = {{ɛ_{0}{A\left\lbrack {\left( {T_{p}/ɛ_{p}} \right) + \left( {T_{ox}/ɛ_{ox}} \right) + \left( {T_{org}/ɛ_{org}} \right)} \right\rbrack}^{- 1}} +}} \\{{2{\pi ɛ}_{0}ɛ_{H_{2}O}R\;{\ln\left\lbrack \frac{\left( {T_{p}/ɛ_{p}} \right) + \left( {T_{ox}/ɛ_{ox}} \right) + \left( {T_{org}/ɛ_{org}} \right) + \left( {T_{H_{2}O}/ɛ_{H_{2}O}} \right)}{\left( {T_{p}/ɛ_{p}} \right) + \left( {T_{ox}/ɛ_{ox}} \right) + \left( {T_{org}/ɛ_{org}} \right)} \right\rbrack}} +} \\{2{\pi ɛ}_{0}R\;{\ln\left\lbrack \frac{\left( {T_{p}/ɛ_{p}} \right) + \left( {T_{ox}/ɛ_{ox}} \right) + \left( {T_{org}/ɛ_{org}} \right) + \left( {T_{H_{2}O}/ɛ_{H_{2}O}} \right) + \left( T_{gap} \right)}{\left( {T_{p}/ɛ_{p}} \right) + \left( {T_{ox}/ɛ_{ox}} \right) + \left( {T_{org}/ɛ_{org}} \right) + \left( {T_{H_{2}O}/ɛ_{H_{2}O}} \right)} \right\rbrack}}\end{matrix}$where C=the capacitance determined in step (e);

-   -   ∈₀=permittivity of free space;    -   A=contact area of the contact means in contact with the topside        of the semiconductor wafer;    -   R=radius of curvature of the contact means;    -   ln=natural log;    -   T_(p)=thickness of an oxide layer (if any) on the surface of the        contact means;    -   ∈_(p)=permittivity of the oxide layer;    -   T_(ox)=thickness of the dielectric layer;    -   ∈_(ox)=permittivity of the dielectric layer;    -   T_(org)=thickness of the organic(s) (if any) overlaying the        dielectric layer,    -   ∈_(org)=permittivity of the organic(s);    -   T_(H) ₂ _(O)=thickness of the water (if any) overlaying the        dielectric layer;    -   ∈_(H) ₂ _(O)=permittivity of the water; and    -   T_(gap)=thickness of a gap between the surface of the contact        means and the topside of the semiconductor wafer adjacent where        the topside supports the surface of the contact means in spaced        relation to the semiconducting material.

The invention is also an apparatus for determining a permittivity of thedielectric layer of a semiconductor wafer. The apparatus includes meansfor contacting a topside of a semiconductor wafer, wherein the contactmeans includes an at least a partially spherical surface formed from aconductive material. The apparatus also includes means for determining athickness of a dielectric layer on the semiconductor wafer havingsemiconducting material underlying the dielectric layer and means formoving the topside of the semiconductor wafer and the at least partiallyspherically surface of the contact means into the contact, therebydefining with the dielectric layer a capacitor. The apparatus furtherincludes means for applying a suitable electrical stimulus, e.g., a CVstimulus, to the contact means and the semiconducting material when thecapacitor is defined and means for determining from the response of thecapacitor to the applied electrical stimulus a capacitance of thecapacitor and for determining therefrom a permittivity of the dielectriclayer as a function of the capacitance and the thickness of thedielectric layer.

Lastly, the invention is a method of determining a permittivity of adielectric layer of a semiconductor wafer comprising: (a) determining athickness of the dielectric layer overlaying semiconducting material ofa semiconductor wafer; (b) moving a topside of the semiconductor waferand a spherical portion of an at least a partially spherical andelectrically conductive surface into contact; (c) applying an electricalstimulus between the electrically conductive surface and thesemiconducting material; (d) determining from the applied electricalstimulus a capacitance of a capacitor comprised of the electricallyconductive surface, the semiconducting material and the dielectric layertherebetween; and (e) determining a permittivity of the dielectric layeras a function of the capacitance determined in step (d) and thethickness of the dielectric layer determined in step (a).

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagrammatic view of a semiconductor wafer having adielectric layer thereon and an apparatus for determining thepermittivity of the dielectric layer;

FIG. 2 is an enlarged view of the distal end of the contact means abovethe semiconductor wafer shown in FIG. 1;

FIG. 3 is a view of the distal end of the contact means in contact withthe topside of the semiconductor wafer shown in FIG. 1 where the topsideincludes water, organics or both on the surface of the dielectric layer;and

FIG. 4 is a view of the distal end of the contact means in contact withthe topside of semiconductor wafer shown in FIG. 1 in the absence ofwater and organics on the surface of the dielectric layer.

DETAILED DESCRIPTION OF THE INVENTION

The present invention will be described with reference to theaccompanying figures where like reference numbers correspond to likeelements.

With reference to FIGS. 1 and 2, a semiconductor wafer testing system 2includes an electrically conductive chuck 4 and a contact means 6. Chuck4 is configured to support a backside 8 of a semiconductor wafer 10which has a dielectric layer 12 overlaying a semiconducting material 14which is in contact with chuck 4. If left exposed to atmosphericconditions for sufficient time, organic(s) 16 and/or water 18 will formon dielectric layer 12.

Desirably, contact means 6 includes at least a partially spherical andconductive surface 20 for contacting a topside 22 of semiconductor water10. The diameter of surface 20 is desirably ≧25 mm. While partiallyspherical, conductive surface 20 is desired, it is envisioned thatsurfaces (not shown) having other shapes can be utilized. Accordingly,the description herein of partially spherical conductive surface 20 isnot to be construed as limiting the invention.

When semiconductor wafer 10 includes organic(s) 16 and/or water 18,topside 22 can be a surface of any one or combination of organic(s) 16,water 18 and dielectric layer 12, although top surface 22 will typicallybe the exposed surface of water 18, as shown in FIG. 2. In FIGS. 1 and2, organic(s) 16 and water 18 are shown as separate layers, andtypically this will be the case. However, this is not to be construed aslimiting the invention since this order can be reversed or organic(s) 16and water 18 can be mixed. e.g., into a dispersion, whereupon suchmixture forms a single layer overlaying dielectric layer 12.

With reference to FIG. 3 and with continuing reference to FIGS. 1 and 2,contact means 6 can be of any suitable form that supports surface 20. InFIG. 1, contact means 6 is illustrated in the form of an elongated probehaving surface 20 positioned at the distal end thereof. However, this isnot to be construed as limiting the invention.

A movement means 24 can be connected to chuck 4, contact means 6 or bothfor moving surface 20 and topside 22 of semiconductor wafer 10 intocontact. An electrical stimulus means 26 can be electrically connectedbetween chuck 4 and surface 20 for applying a suitable test stimulus tosemiconductor wafer 10 when it is received on chuck 4 and surface 20 isin contact with topside 22 of semiconductor wafer 10. For the purpose ofthe present invention, one suitable test stimulus is an AC voltage.However, this is not to be construed as limiting the invention.

Surface 20 of contact means 6 held in spaced relation to semiconductingmaterial 14 by topside 22 defines a capacitor C, wherein dielectriclayer 12, organic(s) 16 and/or water 18 define a dielectric betweencontact means 6 and semiconducting material 14. More specifically, whensurface 20 moves into contact with topside 22, water 18 substantiallydisplaces around surface 20 and surface 20 elastically deforms uponcontact with organic(s) 16 to form a contact area 30. A contact area 31is also formed where surface 20 contacts water 18 adjacent contact area30. Lastly, an air gap 32 is formed between a top surface of water 18and the portion of surface 20 adjacent contact area 31. In response toelectrical stimulus means 26 applying the test stimulus to capacitor C,a measurement means 28 can determine a capacitance C_(T) of capacitor C.

Capacitance C_(T) of capacitor C determined by measurement means 28 isthe sum of a capacitance C₁ of a capacitor C1, formed by the portions ofsurface 20, semiconducting material 14, dielectric layer 12 andorganic(s) 16 in alignment with contact area 30, plus a capacitance C₂of a capacitor C2, formed by the portions of surface 20, semiconductingmaterial 14, dielectric layer 12, organic(s) 16 and water 18 inalignment with contact area 31, plus a capacitance C₃ of a capacitor C3,formed by the portions of surface 20, semiconducting material 14,dielectric layer 12, and organic(s) 16 and/or water 18 in alignment withair gap 32.

When water 18 is not present and dielectric layer 12 is formed from amaterial, such as SiO₂, having a low permittivity, e.g., <3.9, anddielectric layer 12 is relatively thick, e.g., >200 nm, a majority ofcapacitance C_(T) of capacitor C is derived from capacitance C₃ ofcapacitor C3. To this end, it has been theoretically determined thatcapacitance C₃ of capacitor C3 is approximately one order of magnitudegreater than the sum of capacitance C₁ of capacitor C1 and capacitanceC₂ of capacitor C2 when water 18 is not present. As a result, when water18 is not present, the permittivity of dielectric layer 12 can bedetermined within an acceptable tolerance as a function of the measuredcapacitance C_(T) of capacitor C and the theoretical capacitance C₃ ofcapacitor C3. More specifically, the permittivity of dielectric layer 12can be determined within an acceptable tolerance from the measuredcapacitance C_(T) of capacitor C from an equation, e.g., equation EQ 4discussed hereinafter, for capacitance C₃ of capacitor C3 while ignoringcapacitances C₁ and C₂ of capacitors C1 and C2, respectively. However,some amount of water 18 will typically be present. Accordingly, it'sdesirable to determine capacitance C_(T) of capacitor C from the sum ofcapacitances C₁, C₂ and C₃ of capacitors C1, C2 and C3, respectively.

Specifically, capacitance C_(T) of capacitor C can be expressedmathematically by the following equation EQ1:C _(T) =C ₁ +C ₂ +C ₃  EQ1where C_(T)=capacitance of capacitor C;

-   -   C₁=capacitance of capacitor C1=the capacitance resulting from        the materials in alignment with contact area 30;    -   C₂=capacitance of capacitor C2=the capacitance resulting from        the materials in alignment with contact area 31; and    -   C₃ capacitance of capacitor C3=capacitance resulting from the        materials in alignment with gap 32.

Capacitances C₁, C₂ and C₃ of capacitors C1, C2 and C3 can be expressedmathematically by the following equations EQ2, EQ3 and EQ4,respectively:

$\begin{matrix}{{{EQ}\; 2\text{:}\mspace{14mu} C_{1}} = {ɛ_{0}{A\left\lbrack {\left( {T_{p}/ɛ_{p}} \right) + \left( {T_{ox}/ɛ_{ox}} \right) + \left( {T_{org}/ɛ_{org}} \right)} \right\rbrack}^{- 1}}} \\{{{EQ}\; 3\text{:}\mspace{14mu} C_{2}} = {2\pi\; ɛ_{0}ɛ_{H_{2}O}R\;\ln}} \\{\left\lbrack \frac{\left( {T_{p}/ɛ_{p}} \right) + \left( {T_{ox}/ɛ_{ox}} \right) + \left( {T_{org}/ɛ_{org}} \right) + \left( {T_{H_{2}O}/ɛ_{H_{2}O}} \right)}{\left( {T_{p}/ɛ_{p}} \right) + \left( {T_{ox}/ɛ_{ox}} \right) + \left( {T_{org}/ɛ_{org}} \right)} \right\rbrack} \\{{{EQ4}\text{:}\mspace{14mu} C_{3}} = {2\pi\; ɛ_{0}ɛ_{H_{2}O}R\;\ln}} \\{\left\lbrack \frac{\begin{matrix}{\left( {T_{p}/ɛ_{p}} \right) + \left( {T_{ox}/ɛ_{ox}} \right) + \left( {T_{org}/ɛ_{org}} \right) +} \\{\left( {T_{H_{2}O}/ɛ_{H_{2}O}} \right) + \left( T_{gap} \right)}\end{matrix}}{\begin{matrix}{\left( {T_{p}/ɛ_{p}} \right) + \left( {T_{ox}/ɛ_{ox}} \right) + \left( {T_{org}/ɛ_{org}} \right) +} \\\left( {T_{H_{2}O}/ɛ_{H_{2}O}} \right)\end{matrix}} \right\rbrack}\end{matrix}$where ∈₀=permittivity of free space;

-   -   A=contact area 30;    -   R=radius of curvature of surface 20;    -   ln=natural log;    -   T_(p)=thickness of oxide layer (if any) on surface 20;    -   ∈_(p)=permittivity of oxide layer on surface 20;    -   T_(ox)=thickness of dielectric layer 12;    -   ∈_(ox)=permittivity of dielectric layer 12;    -   T_(org)=thickness of organic(s) 16 (if any);    -   ∈_(org)=permittivity of organic(s) 16;    -   T_(H) ₂ _(O)=thickness of water 18 (if any);    -   ∈_(H) ₂ _(O)=permittivity of water 18; and    -   T_(gap)=thickness of gap 32.

As can be seen in equation EQ4, the thickness of gap 32 (T_(gap)) is theonly variable that is not divided by a permittivity. This is because thepermittivity of the air in gap 32 is one (1). Hence, in equation EQ4,T_(gap) will dominate the thickness of the other materials divided bytheir permittivities. Similarly, when summing equations EQ2, EQ3 and EQ4to determine the capacitance C_(T) of capacitor C, T_(gap) willtypically be the primary contributor to capacitance C_(T).

Substituting equations EQ2, EQ3 and EQ4 for C₁, C₂ and C₃, respectively,in equation 1, the capacitance C_(T) of capacitor C can be determined bysolving the sum of equations EQ2, EQ3 and EQ4 simultaneously in aniterative manner utilizing one or more well known numerical techniques.

With reference to FIG. 4 and with continuing reference to all previousfigures, in practice it is desirable to eliminate the effect oforganic(s) 16 and/or water 18 oil the determination of the permittivityof dielectric layer 12 since determining the thickness of organic(s) 16and/or water 18 can be difficult and inaccurate. To this end, any delaybetween determining the thickness of organic(s) 16 and/or water 18 anddetermining capacitance C_(T) of capacitor C may result in one or bothof said thicknesses changing whereupon the determination of capacitanceC_(T) is affected. Accordingly, prior to surface 20 of contact means 6moving into contact with topside 22 of semiconductor wafer 10,organic(s) 16 and/or water 18 are desirably desorbed from semiconductorwafer 10 in a manner known in the art, e.g. heating semiconductor wafer10 to an elevated temperature. After desorbing organic(s) 16 and/orwater 18, surface 20 and topside 22, in this case the topside ofdielectric layer 12, can be moved directly into contact.

Desirably, surface 20 of contact means 6 does not include an oxidelayer. However, if surface 20 includes an oxide layer (not shown), suchoxide layer is desirably conductive. Suitable materials for surface 20include platinum and iridium. However, this is not to be considered aslimiting the invention since surface 20 can be formed from any suitablematerial that either does not form an oxide layer or forms a conductiveoxide layer.

If capacitance C_(T) of capacitor C is determined after organic(s) 16and/or water 18 are desorbed from semiconductor wafer 10, and contactmeans 6 does not include an oxide layer on surface 20, equation EQ4 canbe reduced to the form shown in the following equation EQ5:

${{EQ5}:\mspace{11mu} C_{3}} = {2\pi\; ɛ_{0}ɛ\; R\;{\ln\left\lbrack \frac{\left( {T_{ox}/ɛ_{ox}} \right) + \left( T_{gap} \right)}{\left( {T_{ox}/ɛ_{ox}} \right)} \right\rbrack}}$If the radius R of curvature of surface 20 is large and the diameter ofperimeter 34 is also large, the operation (T_(ox)/∈_(ox)) in thenumerator of equation EQ5 can be ignored.

As can be seen, in order to determine capacitance C₃ in equations EQ4and EQ5, the thickness of dielectric layer 12 (T_(ox)) is required.T_(ox) can be determined in any manner known in the art, such asellipsometry. Once a value has been determined for T_(ox), this valuecan be provided to measurement means 28 for calculation of thepermittivity ∈_(ox) of dielectric layer 12.

In equations EQ3 and EQ4, the radius R of curvature of surface 20 isutilized in addition to the thickness and permittivity of dielectriclayer 12, organic(s) 16, water 18 and any oxide on contact means 6. Morespecifically, in equations EQ3 and EQ4, the radius R of curvature ofsurface 20 is directly proportioned to capacitance C₂ or C₃, as the casemay be. Hence, the larger the radius R, the larger the value ofcapacitance C_(T) of capacitor C. It has been determined that surface 20having a radius R>12.5 mm (diameter>25 mm), that is about one order ofmagnitude greater than the diameter of the distal end of a prior artconductive elastic probe, yields a value of capacitor C_(T) that can bemeasured readily.

In equations EQ4 and EQ5, the thickness of gap 32 T_(gap) is utilized todetermine capacitance C₃ of capacitor C3. The thickness of gap 32T_(gap) in equations EQ4 and EQ5 is the average thickness of gap 32.More specifically, with specific reference to FIG. 3, the thickness ofgap 32 T_(gap) used in equations EQ4 and EQ5 can be determined utilizingthe following equation EQ6:T _(gap) =R(cos θ₂−cos θ₃)  EQ6where R=radius of curvature of surface 20;

-   -   θ₂=an angle between a center 36 of contact area 30 and a        perimeter 34 of contact area 31 measured with respect to a        center 38 of radius R; and    -   θ₃=an angle, measured with respect to center 38 of radius R,        between center 36 of contact area 30 and a perimeter 40 of        surface 20 where surface 20 is no longer in opposition with        topside 22 of semiconductor wafer 10.

In FIG. 3, topside 22 includes the surface of organic(s) 16 formingcontact area 30, the surface of water 18 forming contact area 31 and thesurface of water 18 in alignment with gap 32. Prior to moving surface 20into contact with topside 22, however, the top surface of water 18defines topside 22 as shown in FIG. 2. Hence, as can be seen, thematerial(s) comprising topside 22 can vary depending upon whethersurface 20 is in contact therewith.

If water 18 is present, the thickness of water 18 T_(H) ₂ _(O) inequation EQ4 is the average thickness of water 18 in alignment withcontact area 31. More specifically, with specific reference to FIG. 3,the thickness of water 18 T_(H) ₂ _(O) used in equation EQ3 can bedetermined utilizing the following equation EQ7:T _(H) ₂ _(O) =R(cos θ₁−cos θ₂)  EQ7where R=radius of curvature of surface 20;

-   -   θ₁=an angle between center 36 and a perimeter 35 of contact area        30 measured with respect to center 38 of radius R; and    -   θ₂=an angle, measured with respect to center 38 of radius R,        between center 36 and the perimeter 34 of contact area 31.

With specific reference to FIG. 4, if topside 22 has been desorbed ofwater 18 and/or organic(s) 16, the thickness of gap 32 T_(gap) used inequation EQ4 can be determined utilizing the following equation EQ8:T _(gap) =R(cos θ₁−cos θ₂)  EQ8where R=radius of curvature of surface 20;

-   -   θ₁=an angle between center 36 and perimeter 35 of contact area        30 measured with respect to center 38 of radius R; and    -   θ₂=an angle, measured with respect to center 38 of radius R,        between center 36 and perimeter 40 of surface 20 where surface        20 is no longer in opposition with topside 22 of semiconductor        wafer 10.

As can be seen, the present invention enables the permittivity of adielectric layer on a semiconductor wafer to be determined to anacceptable tolerance as a function of the thickness of dielectric layer12 and the measured capacitance C_(T) of capacitor C. The presentinvention is especially useful for determining the permittivity ofrelatively thick dielectric layers having relatively low permittivities.

The present invention has been described with reference to the preferredembodiment. Obvious modifications and alterations will occur to othersupon reading and understanding the preceding detailed description. It isintended that the present invention be construed as including all suchmodifications and alterations insofar as they come within the scope ofthe appended claims or the equivalents thereof.

1. A method of determining a permittivity of a dielectric layer of asemiconductor wafer comprising: (a) providing a means for contacting atopside of a semiconductor wafer, the contact means including at least apartially spherical surface formed from a conductive material; (b)determining a thickness of a dielectric layer on the semiconductor waferhaving semiconducting material underlying the dielectric layer; (c)causing the at least partially spherical surface of the contact means tocontact the topside of the semiconductor wafer thereby defining acapacitor, wherein the capacitance of the capacitor is comprised of afirst capacitance resulting from materials in alignment with a contactarea of the contact means in contact with the top surface of thesemiconductor wafer and a second capacitance resulting from materials inalignment with a gap defined between the top surface of thesemiconductor wafer and a surface of the contact means not in contactwith the top surface surrounding the contact area; (d) applying anelectrical stimulus to the contact means and the semiconducting materialwhen the capacitor is defined; (e) determining the capacitance of thecapacitor from the response thereof to the applied electrical stimulus;and (f) determining a permittivity of the dielectric layer as a functionof the capacitance determined in step (e), the thickness of thedielectric layer determined in step (b) and the thickness of the gapsurrounding the contact area.
 2. The method of claim 1, wherein thetopside of the semiconductor wafer comprises at least one of: a surfaceof the dielectric layer opposite the semiconducting material; and asurface of organic(s) and/or water overlaying the surface of thedielectric layer opposite the semiconducting material.
 3. The method ofclaim 2, wherein the permittivity of the dielectric layer (∈_(ox)) isdetermined utilizing the formula: $\begin{matrix}{C = {{ɛ_{0}{A\left\lbrack {\left( {T_{p}/ɛ_{p}} \right) + \left( {T_{ox}/ɛ_{ox}} \right) + \left( {T_{org}/ɛ_{org}} \right)} \right\rbrack}^{- 1}} +}} \\{{2{\pi ɛ}_{0}ɛ_{H_{2}O}R\;{\ln\left\lbrack \frac{\left( {T_{p}/ɛ_{p}} \right) + \left( {T_{ox}/ɛ_{ox}} \right) + \left( {T_{org}/ɛ_{org}} \right) + \left( {T_{H_{2}O}/ɛ_{H_{2}O}} \right)}{\left( {T_{p}/ɛ_{p}} \right) + \left( {T_{ox}/ɛ_{ox}} \right) + \left( {T_{org}/ɛ_{org}} \right)} \right\rbrack}} +} \\{2{\pi ɛ}_{0}R\;{\ln\left\lbrack \frac{\left( {T_{p}/ɛ_{p}} \right) + \left( {T_{ox}/ɛ_{ox}} \right) + \left( {T_{org}/ɛ_{org}} \right) + \left( {T_{H_{2}O}/ɛ_{H_{2}O}} \right) + \left( T_{gap} \right)}{\left( {T_{p}/ɛ_{p}} \right) + \left( {T_{ox}/ɛ_{ox}} \right) + \left( {T_{org}/ɛ_{org}} \right) + \left( {T_{H_{2}O}/ɛ_{H_{2}O}} \right)} \right\rbrack}}\end{matrix}$ where C=the capacitance determined in step (e);∈₀=permittivity of free space; A=contact area of the contact means incontact with the topside of the semiconductor wafer; R=radius ofcurvature of the contact means; In=natural log; T_(p)=thickness of anoxide layer (if any) on the surface of the contact means;∈_(p)=permittivity of the oxide layer; T_(ox)=thickness of thedielectric layer; ∈_(ox)=permittivity of the dielectric layer;T_(org)=thickness of the organic(s) (if any) overlaying the dielectriclayer; ∈_(org)=permittivity of the organic(s); T_(H) ₂ _(O)=thickness ofthe water (if any) overlaying the dielectric layer; ∈_(H) ₂_(O)=permittivity of the water; and T_(gap)=thickness of the gapsurrounding the contact area.
 4. The method of claim 1, furtherincluding desorbing at least one of water and organic(s) from a surfaceof the dielectric layer.
 5. The method of claim 1, wherein the at leastpartially spherical surface is formed from a conductive material thateither does not form an oxide layer or forms a conductive oxide on thesurface thereof.
 6. A system for determining a permittivity of adielectric layer of a semiconductor wafer comprising: means forcontacting a topside of a semiconductor wafer, the contact meansincluding at least a partially spherical surface formed from aconductive material; means for determining a thickness of a dielectriclayer on the semiconductor wafer having semiconducting materialunderlying the dielectric layer; means for moving the topside of thesemiconductor wafer and the at least partially spherical surface of thecontact means into contact thereby defining with the dielectric layer acapacitor having a capacitance comprised of a first capacitanceresulting from materials in alignment with a contact area of the contactmeans in contact with the top surface of the semiconductor wafer and asecond capacitance resulting from materials in alignment with a gapdefined between the top surface of the semiconductor wafer and a surfaceof the contact means not in contact with the top surface surrounding thecontact area; means for applying an electrical stimulus to the contactmeans and the semiconducting material when the capacitor is defined; andmeans for determining a capacitance of the capacitor from the responseof the capacitor to the applied electrical stimulus; and means fordetermining a permittivity of the dielectric layer as a function of thecapacitance, the thickness of the dielectric layer and a thickness ofthe gap surrounding the contact area.
 7. The system of claim 6, whereinthe topside of the semiconductor wafer comprises at least one of: asurface of the dielectric layer opposite the semiconducting material;and a surface of organic(s) and/or water overlaying the surface of thedielectric layer opposite the semiconducting material.
 8. The system ofclaim 6, further including means for desorbing at least one of water andorganic(s) from a surface of the dielectric layer.
 9. The apparatus ofclaim 6, wherein the at least partially spherical surface is formed froma conductive material that either does not form an oxide layer or formsa conductive oxide on the surface thereof.
 10. The system of claim 6,wherein the means for determining the permittivity of the dielectriclayer utilizes the formula: $\begin{matrix}{C = {{ɛ_{0}{A\left\lbrack {\left( {T_{p}/ɛ_{p}} \right) + \left( {T_{ox}/ɛ_{ox}} \right) + \left( {T_{org}/ɛ_{org}} \right)} \right\rbrack}^{- 1}} +}} \\{{2{\pi ɛ}_{0}ɛ_{H_{2}O}R\;{\ln\left\lbrack \frac{\left( {T_{p}/ɛ_{p}} \right) + \left( {T_{ox}/ɛ_{ox}} \right) + \left( {T_{org}/ɛ_{org}} \right) + \left( {T_{H_{2}O}/ɛ_{H_{2}O}} \right)}{\left( {T_{p}/ɛ_{p}} \right) + \left( {T_{ox}/ɛ_{ox}} \right) + \left( {T_{org}/ɛ_{org}} \right)} \right\rbrack}} +} \\{2{\pi ɛ}_{0}R\;{\ln\left\lbrack \frac{\left( {T_{p}/ɛ_{p}} \right) + \left( {T_{ox}/ɛ_{ox}} \right) + \left( {T_{org}/ɛ_{org}} \right) + \left( {T_{H_{2}O}/ɛ_{H_{2}O}} \right) + \left( T_{gap} \right)}{\left( {T_{p}/ɛ_{p}} \right) + \left( {T_{ox}/ɛ_{ox}} \right) + \left( {T_{org}/ɛ_{org}} \right) + \left( {T_{H_{2}O}/ɛ_{H_{2}O}} \right)} \right\rbrack}}\end{matrix}$ where C=the capacitance determined in step (e);∈₀=permittivity of free space; A=contact area of the contact means incontact with the topside of the semiconductor wafer; R=radius ofcurvature of the contact means; In=natural log; T_(p)=thickness of anoxide layer (if any) on the surface of the contact means;∈_(p)=permittivity of the oxide layer; T_(ox)=thickness of thedielectric layer; ∈_(ox)=permittivity of the dielectric layer;T_(org)=thickness of the organic(s) (if any) overlaying the dielectriclayer; ∈_(org)=permittivity of the organic(s); T_(H) ₂ _(O)=thickness ofthe water (if any) overlaying the dielectric layer; ∈_(H) ₂_(O)=permittivity of the water; and T_(gap)=thickness of the gapsurrounding the contact area.
 11. A method of determining a permittivityof a dielectric layer of a semiconductor wafer comprising: (a)determining a thickness of the dielectric layer overlayingsemiconducting material of a semiconductor wafer; (b) moving a topsideof the semiconductor wafer and a spherical portion of an at leastpartially spherical and electrically conductive surface into contact;(c) applying an electrical stimulus between the electrically conductivesurface and the semiconducting material; (d) determining from theapplied electrical stimulus a capacitance of a capacitor comprised of afirst capacitance resulting from materials in alignment with a contactarea of the contact means in contact with the top surface of thesemiconductor wafer and a second capacitance resulting from materials inalignment with a gap between the top surface and the contact meanssurrounding the contact area; and (e) determining a permittivity of thedielectric layer as a function of the capacitance determined in step(d), the thickness of the dielectric layer determined in step (a) and athickness of the gap surrounding the contact area.
 12. The method ofclaim 11, wherein the topside of the semiconductor wafer comprises atleast one of: a surface of the dielectric layer opposite thesemiconducting material; and a surface of organic(s) and/or wateroverlaying the surface of the dielectric layer opposite thesemiconducting material.
 13. The method of claim 11, further including,prior to step (b), desorbing at least one of water and organic(s) from asurface of the dielectric layer.
 14. The method of claim 11, wherein theelectrically conductive surface is formed from a material that eitherdoes not form an oxide layer thereon or forms a conductive oxidethereon.
 15. The method of claim 11, wherein the permittivity of thedielectric layer (∈_(ox)) is determined by solving the following formulafor ∈_(ox): $\begin{matrix}{C = {{ɛ_{0}{A\left\lbrack {\left( {T_{p}/ɛ_{p}} \right) + \left( {T_{ox}/ɛ_{ox}} \right) + \left( {T_{org}/ɛ_{org}} \right)} \right\rbrack}^{- 1}} +}} \\{{2{\pi ɛ}_{0}ɛ_{H_{2}O}R\;{\ln\left\lbrack \frac{\left( {T_{p}/ɛ_{p}} \right) + \left( {T_{ox}/ɛ_{ox}} \right) + \left( {T_{org}/ɛ_{org}} \right) + \left( {T_{H_{2}O}/ɛ_{H_{2}O}} \right)}{\left( {T_{p}/ɛ_{p}} \right) + \left( {T_{ox}/ɛ_{ox}} \right) + \left( {T_{org}/ɛ_{org}} \right)} \right\rbrack}} +} \\{2{\pi ɛ}_{0}R\;{\ln\left\lbrack \frac{\left( {T_{p}/ɛ_{p}} \right) + \left( {T_{ox}/ɛ_{ox}} \right) + \left( {T_{org}/ɛ_{org}} \right) + \left( {T_{H_{2}O}/ɛ_{H_{2}O}} \right) + \left( T_{gap} \right)}{\left( {T_{p}/ɛ_{p}} \right) + \left( {T_{ox}/ɛ_{ox}} \right) + \left( {T_{org}/ɛ_{org}} \right) + \left( {T_{H_{2}O}/ɛ_{H_{2}O}} \right)} \right\rbrack}}\end{matrix}$ where C=the capacitance determined in step (e);∈₀=permittivity of free space; A=contact area of the contact means incontact with the topside of the semiconductor wafer; R=radius ofcurvature of the contact means; In=natural log; T_(p)=thickness of anoxide layer (if any) on the surface of the contact means;∈_(p)=permittivity of the oxide layer; T_(ox)=thickness of thedielectric layer; ∈_(ox)=permittivity of the dielectric layer;T_(org)=thickness of the organic(s) (if any) overlaying the dielectriclayer; ∈_(org)=permittivity of the organic(s); T_(H) ₂ _(O)=thickness ofthe water (if any) overlaying the dielectric layer; ∈_(H) ₂_(O)=permittivity of the water; and T_(gap)=thickness of the gapsurrounding the contact area.